The present invention relates to an intake control device for an internal combustion engine of the type having an auxiliary intake passage.
Laying-open Japanese patent application No. 54-150516 discloses an intake control device for an internal combustion engine. The intake control device comprises an auxiliary intake passage branched off from a main intake passage at a portion upstream of a shut off valve disposed downstream of a throttle valve, and joined to the main intake passage at a portion downstream of the shut off valve. This auxiliary intake passage is so designed as to admit intake air into a combustion chamber in such a direction as to cause generation of swirl within the combustion chamber. When, in operation, the engine idles, the throttle valve is closed and shut off valve is closed, too. Under this condition, intake air flows past a clearance formed around the throttle valve, then through the auxiliary intake passage bypassing the shut off valve and then into the combustion chamber.
An object of the present invention is to provide an intake control device for an internal combustion engine which provides a sufficient amount of scavenging air at engine low load operation including idle operation.